South LA's public health enemy: WHO declares diesel fumes to be cancerous

June 13, 2012, 12:11 p.m.

The World Health Organization declared diesel fumes to be a Group 1 carcinogen on Tuesday, putting it in the same class as asbestos and ultraviolet radiation. (Credit: James Burry/Flickr Creative Commons)

Diesel fumes are now in the same cancerous class as asbestos, smoking and ultraviolet radiation.

That's what the World Health Organization (WHO) said on Tuesday when it became the first to rate diesel fumes as a Group 1 (known) carcinogen, declaring that the fumes cause lung cancer and are more carcinogenic than secondhand cigarette smoke.

In other circles, diesel fumes are only rated as a potential or likely carcinogen.

John Froines, a professor emeritus of chemical toxicology at UCLA, called the announcement a "major event." In 1998, Froines was chair of the Scientific Review Panel (SRP), a committee which reviews and determines the scientific validity of documents and research by three California state agencies, including the Air Resources Board (ARB). The SRP will makes recommendations based on its evaluation of the data, which are then voted upon by the state agencies.

"In 1998, our committee recommended that diesel be declared a toxic air contaminant because of human lung cancer," said Froines. "So we actually made the recommendation based on the state's documents 14 years ago."

The agency in that case was the ARB, and they were "the first body that declared diesel a human lung carcinogen," Froines says. The panel he chaired validated those findings.

That was 14 years ago – and the WHO's organization was just on Tuesday. Froines said that's because the body within the WHO that made the declaration, the International Agency for Research on Cancer (IARC), is very deliberate.

"[The IARC] is the most prestigious body in the world and they're very conservative," said Froines, adding that if the IARC says something, it's going to go to great lengths to verify that it's factual. "The science that goes into determination is outstanding so that this is something that one can take with confidence. It's an immense finding."

Since 1998, Froines explained, the "weight of the evidence has grown remarkably." He directs the Southern California Particle Center at UCLA, and one of the findings that group has made is that diesel particles are unusually tiny.

"They're called ultra-fine particles to differentiate themselves from larger particles, and those small particles from diesel engines penetrate cells in the lung," he said. "So when you breathe, it's not just that particles deposit on the lung – they enter the lung cells themselves." With information like that, he's been able to create a "roadmap" that occurs when a person breathes these particles, and the endpoints of that roadmap is bleak: Heart disease. Asthma. Lung and bladder cancer.

Froines says in light of the WHO's announcement, there's a lot to be done. Most of California's air pollution problems comes from mobile or portable sources, Froines explained – trucks, railroad diesel trains, tractors. He said it was now up to the ARB to "establish whatever new regulations are appropriate."

Los Angeles was never known for fresh air, though, and Froines highlighted some of the problem areas – the ports and freeways, in particular. "We live in an environment dominated by diesel vehicles," he said.

Dense South Los Angeles, cordoned off by the 10, 105 and 710 freeways, with the 110 going straight through its heart, is a textbook example of a place with a high prevalence of diesel fumes. And although it rates moderate on the Air Quality Index, add to that the diesel trucks that run up and down the industrial Alameda Corridor to the east (and lots of other southside thoroughfares), and the WHO's concern about fumes suddenly hits a little closer to home.

"The Alameda Corridor is where a lot of locomotives that are leaving L.A. with goods for the rest of the country travel," said Andrea Hricko, a professor of preventive medicine at USC's Keck School of Medicine, adding that even though they travel in a trench, exhaust still comes out of that trench. "You've got people in South L.A. who are exposed to that exhaust."

As for the freeways, Hricko said the 710, 605 and 60 are especially bad. "Elemental carbon levels as a marker for diesels is four times higher on the 710 than in West L.A.," she said. And at the Florence exit off the 110, diesel trucks make up 4.26 percent of the daily traffic volume; that's more than 13,500 trucks a day, according to the California Department of Transportation.

"One of the important things to come out of this [WHO] ruling is that it's time for some of the industries that have been really trying to say that diesel doesn't cause cancer to step up to the plate, and recognize that their industries really need to clean up much more than they've been doing," said Hricko. "If you look at Southern California, you've got people who live really close to the ports and rail yards at really serious risk."

Froines agreed. "In the long run, diesel needs to be eliminated or controlled to a degree that the emissions are not associated with risk," he said.

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